无法在DelegateProxyType (rxSwift)中使用proxyForObject函数

import RxSwift
import RxCocoa

class MyDelegateProxy: DelegateProxy<SomeDelegate, SomeObject>, DelegateProxyType {

    static func currentDelegate(for object: SomeObject) -> SomeDelegate? {
        return object.delegate
    }

    static func setCurrentDelegate(_ delegate: SomeDelegate?, to object: SomeObject) {
        object.delegate = delegate
    }

    static func proxyForObject(_ object: AnyObject) -> AnyObject {
        let delegateProxy = MyDelegateProxy(parentObject: object as! SomeObject)
        return delegateProxy
    }
}

extension Reactive where Base: SomeObject {
    var delegate: DelegateProxy<SomeDelegate, SomeObject> {
        return MyDelegateProxy.proxyForObject(base)
    }
}